Insertion of heteroallenes into the rhenium-hydride bond

Dithioformato [Re{η²-SC(H)S}(NO)P₃]BPh₄ (1), thioformamido [Re{η²-RNC(H)S}(NO)P₃]BPh₄ (2) (R = Et, p-tolyl), formamido [Re{η²-PhNC(H)O}(NO)P₃]BPh₄ (3) and formamidinato [Re{η²-p-tolylNC(H)Np-tolyl}(NO)P₃]BPh₄ (4) (P = PPh₂OEt) complexes were prepared by allowing the hydride ReH₂(NO)P₃ to react first with triflic acid and then with the appropriate heteroallene CS₂, RNCS, PhNCO and p-tolylNCNp-tolyl. Treatment of the ReH₂(NO)L(PPh₃)₂ [L = P(OEt)₃, PPh(OEt)₂] and ReH₂(NO)(PPh₃)₃ hydrides first with triflic acid and then with isothiocyanate RNCS (R = Et, p-tolyl) gave the [Re{η²-RNC(H)S}(NO){P(OEt)₃}(PPh₃)₂]BPh₄ (5, 6) and [Re(η²-RNC(H)S)(NO)(PPh₃)₃]BPh₄ (7) derivatives. Depending on the nature of the phosphite, instead, the reaction of ReH₂(NO)L(PPh₃)₂ and ReH₂(NO)(PPh₃)₃ hydrides first with CF₃SO₃H and then with isocyanate R1NCO (R1 = Ph, p-tolyl) gave the chelate [Re{η²-R1NC(H)O}(NO){P(OEt)₃}(PPh₃)₂]BPh₄ (8) and [Re{η²-R1NC(H)O}(NO)(PPh₃)₃]BPh₄(10) complexes with P(OEt)₃ or PPh₃, while the η¹-coordinate [Re{η¹-RNC(H)S}(NO){PPh(OEt)₂}₂(PPh₃)₂]BPh₄ (9) derivative was obtained with the PPh(OEt)₂ phosphite ligand. η¹-Coordinate dithioformato [Re{η¹-SC(H)S}(NO){PPh(OEt)₂}₂(PPh₃)₂]BPh₄ (11) and formato [Re{η¹-OC(H)O}(NO){PPh(OEt)₂}₂(PPh₃)₂]BPh₄ (12) complexes, as well as the formamidinato [Re{η²-p-tolylNC(H)Np-tolyl}(NO){P(OEt)₃}(PPh₃)₂]BPh₄ (13) derivative were also prepared.     

Influence of chain length on mono- versus di-alkylation in the reactivity of [Pt2(μ-S)2(PPh3)4] towards α,ω-dihalo-n-alkanes; a synthetic route to platinum(II) ω-haloalkylthiolate complexes

The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with α,ω-dibromoalkanes Br(CH₂)_nBr (n = 4, 5, 6, 8, 12) gave mono-alkylated [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ and/or di-alkylated [Pt₂(μ-S(CH₂)_nS}(PPh₃)₄]²⁺ products, depending on the alkyl chain length and the reaction conditions. With longer chains (n = 8, 12), intramolecular di-alkylation does not proceed in refluxing methanol, with the mono-alkylated products [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ being the dominant products when excess alkylating agent is used. The bridged complex [{Pt₂(μ-S)₂(PPh₃)₄}₂{μ-(CH₂)₁₂}]²⁺ was accessible from the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of Br(CH₂)₁₂Br. [Pt₂(μ-S){μ-S(CH₂)₄Br}(PPh₃)₄]⁺ can be cleanly isolated as its BPh₄⁻ salt, but undergoes facile intramolecular di-alkylation at −18 °C, giving the known species [Pt₂(μ-S(CH₂)₄S}(PPh₃)₄]²⁺. The reaction of I(CH₂)₆I with [Pt₂(μ-S)₂(PPh₃)₄] similarly gives [Pt₂(μ-S){μ-S(CH₂)₆I}(PPh₃)₄]⁺, which is fairly stable towards intramolecular di-alkylation once isolated. These reactions provide a facile route to ω-haloalkylthiolate complexes which are poorly defined in the literature. X-ray crystal structures of [Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]BPh₄ and [Pt₂(μ-S(CH₂)₅S}(PPh₃)₄](BPh₄)₂ are reported, together with a study of these complexes by electrospray ionisation mass spectrometry. All complexes fragment by dissociation of PPh₃ ligands, and the bromoalkylthiolate complexes show additional fragment ions [Pt₂(μ-S){μ-S(CH₂)_n−2CHCH₂}(PPh₃)_m]⁺ (m = 2 or 3; m ≠ 4), most significant for n = 4, formed by elimination of HBr.     

Synthesis, spectroscopy and structural characterization of silver(I) complexes containing unidentate N-donor azole-type ligands

From the interaction between azole-type ligands L and AgX (X = NO₃ or ClO₄) or [AgX(PPh₃)_n] (X = Cl, n = 3; X = MeSO₃, n = 2), new ionic mononuclear [Ag(L)₂]X and [Ag(PPh₃)₃L][X] or neutral mono-([Ag(PPh₃)_nL(X)]) or di-nuclear ([{Ag(PPh₃)(L)(μ-X)}₂]) complexes have been obtained which have been characterized through elemental analysis, conductivity measurements, IR, ¹H NMR and, in some cases, also by ³¹P{¹H} NMR spectroscopy, and single-crystal X-ray studies. Stoichiometries and molecular structures are dependent on the nature of the azole (steric hindrance and basicity), of the counter ion, and on the number of the P-donor ligands in the starting reactants. Solution data are consistent with partial dissociation of the complexes, occurring through breaking of both Ag-N and Ag-P bonds.     

Heterobimetallic platinum-bismuth aggregates derived from [Pt2(μ-S)2(PPh3)4]

The metalloligand [Pt₂(μ-S)₂(PPh₃)₄] reacts with Bi(S₂CNEt₂)₃ or Bi(S₂COEt)₃ in methanol to produce the orange cationic adducts [Pt₂(μ-S)₂(PPh₃)₄Bi(S₂CNEt₂)₂]⁺ and [Pt₂(μ-S)₂(PPh₃)₄Bi(S₂COEt)₂]⁺, respectively, isolated as their hexafluorophosphate salts. An X-ray structure determination on [Pt₂(μ-S)₂(PPh₃)₄Bi(S₂CNEt₂)₂]PF₆ reveals the presence of a six-coordinated bismuth centre with an approximately nido-pentagonal bipyramidal coordination geometry. Fragmentation pathways for both complexes have been probed using electrospray ionisation mass spectrometry; ions [Pt₂(μ-S)₂(PPh₃)₂Bi(S₂CXEt_n)₂]⁺ (X = O, n = 1, X = N, n = 2) are formed by selective loss of two PPh₃ ligands, and at higher cone voltages the species [(Ph₃P)PtS₂Bi]⁺ is observed. Ions formed by loss of CS₂ are also observed for the xanthate but not the dithiocarbamate ions.     

Reactions of the pentamethylcyclopentadienyl trisulfido tungsten with M′Cl2 (M′ = Zn, Cd, Hg): Isolation and structural characterization of [PPh4][(η-C5Me5)WS3(ZnCl2)] and [{(η-C5Me5)WS3}2Hg]

Reactions of [PPh₄][(η⁵-C₅Me₅)WS₃] with equimolar M′Cl₂ (M′ = Zn, Cd) in MeCN or 0.5 equiv. of HgCl₂ in DMF afforded two binuclear clusters [PPh₄][(η⁵-C₅Me₅)WS₃(M′Cl₂)] (1: M′ = Zn; 2: M′ = Cd) and one trinuclear cluster [{(η⁵-C₅Me₅)WS₃}₂Hg] (3). Compounds 1-3 were characterized by elemental analysis, IR, UV-Vis, ¹H NMR and X-ray crystallography. Compound 1 may be viewed as a 1:1 composite of [PPh₄][(η⁵-C₅Me₅)WS₃] and ZnCl₂, in which one [(η⁵-C₅Me₅)WS₃]⁻ anion binds a ZnCl₂ moiety via two μ-S atoms. In the structure of 3, two [(η⁵-C₅Me₅)WS₃]⁻ anions coordinate the central Hg atom via two μ-S atoms, forming an unique bent linear structure. In addition, internal redox reactions of [PPh₄][(η⁵-C₅Me₅)WS₃] under the presence of M′Cl₂ (M′ = Zn, Cd, Hg) in high concentrations were discussed.     

Thallium(III) complexes of the metalloligands [Pt2(μ-S)2(PPh3)4] and [Pt2(μ-Se)2(PPh3)4]

Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with the diarylthallium(III) bromides Ar₂TlBr [Ar = Ph and p-ClC₆H₄] in methanol gave good yields of the thallium(III) adducts [Pt₂(μ-S)₂(PPh₃)₄TlAr₂]⁺, isolated as their salts. The corresponding selenide complex [Pt₂(μ-Se)₂(PPh₃)₄TlPh₂]BPh₄ was similarly synthesised from [Pt₂(μ-Se)₂(PPh₃)₄], Ph₂TlBr and NaBPh₄. The reaction of [Pt₂(μ-S)₂(PPh₃)₄] with PhTlBr₂ gave [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]⁺, while reaction with TlBr₃ gave the dibromothallium(III) adduct [Pt₂(μ-S)₂(PPh₃)₄TlBr₂]⁺[TlBr₄]⁻. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt₂(μ-S)₂(PPh₃)₄TlPh₂]BPh₄, [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]BPh₄ and [Pt₂(μ-S)₂(PPh₃)₄TlBr₂][TlBr₄] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl-S and Pt?Tl distances, and an increasing S-Tl-S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported.     

Reaction of iron and ruthenium halogenide complexes with GaCp and AlCp: Insertion, Cp transfer reactions and orthometallation

The reactions of the Fe(II) and Ru(II) halogenide complexes [Fe(PPh₃)₂Br₂], [Fe(NCCH₃)₂Br₂], [Ru(PPh₃)₃Cl₂], and [Ru(dmso)₄Cl₂] with GaCp^∗ and AlCp^∗, respectively, are investigated. The reactions of [FeBr₂L₂] with ECp^∗ exclusively proceed via Cp^∗ transfer, leading to [FeCp^∗(GaCp^∗)(GaBr₂)(PPh₃)] (1) (L = PPh₃, E = Ga), [FeCp^∗(GaCp^∗)₂ (GaBr₂)] (2) (L = NCCH₃, E = Ga) and [FeCp^∗(μ³-H)(κ²-(C₆H₄)PPh₂)(AlCp^∗)(AlBr₂)] (3) (L = PPh₃, E = Al), the latter of which is formed via orthometallation of one PPh₃ ligand. The reaction of [Ru(dmso)₄Cl₂] leads to the homoleptic complex [Ru(GaCp^∗)₆Cl₂] (4) in high yields, while [Ru(PPh₃)₃Cl₂] gives 4 in rather low yields. The reason for this difference in reactivity is investigated and it is shown that Cp^∗ transfer and orthometallation are the limiting side reactions of the reaction of [Ru(PPh₃)₃Cl₂] with GaCp^∗. All compounds were characterized by NMR spectroscopy, and single crystal X-ray diffraction studies were performed for 1, 3, and 4.     

Further studies on the coordination chemistry of [Pt2(μ-S)2(PPh3)4] towards indium(III) substrates

The reactivity of the metalloligand [Pt₂(μ-S)₂(PPh₃)₄] towards a variety of indium(III) substrates has been explored. Reaction with excess In(NO₃)₃ and halide (KBr or NaI) gave the four-coordinate adducts [Pt₂(μ-S)₂(PPh₃)₄InX₂]⁺[InX₄]⁻ (X = Br, I). An X-ray structure determination on the iodo complex revealed a slightly distorted tetrahedral coordination geometry at indium. In contrast, reaction of [Pt₂(μ-S)₂(PPh₃)₄] with indium(III) chloride was more complex; the ion [Pt₂(μ-S)₂(PPh₃)₄InCl₂]⁺ was initially observed in solution (using ESI mass spectrometry), and isolated as its BPh₄⁻ salt. Analysis of [Pt₂(μ-S)₂(PPh₃)₄InCl₂]⁺[BPh₄]⁻ by ESI MS showed the parent cation when analysed in MeCN solution. However in solutions containing methanol, partial solvolysis occurred to give the di-indium species [{Pt₂(μ-S)₂(PPh₃)₄InCl(OMe)}₂]²⁺ (proposed to contain an In₂(μ-OMe)₂ unit with five-coordinate indium) and its fragment ion [Pt₂(μ-S)₂(PPh₃)₄InCl(OMe)]⁺. Reaction of [Pt₂(μ-S)₂(PPh₃)₄] with InCl₃·3H₂O, 8-hydroxyquinoline (HQ) and trimethylamine in methanol gave the adduct [Pt₂(μ-S)₂(PPh₃)₄InQ₂]⁺, isolated as its PF₆⁻ salt. The same cationic complex is formed when [Pt₂(μ-S)₂(PPh₃)₄] is reacted with InQ₃ in methanol, but in this case the product is contaminated with the mononuclear complex [(Ph₃P)₂PtQ]⁺ formed by disintegration of the trinuclear complex [Pt₂(μ-S)₂(PPh₃)₄InQ₂]⁺ with byproduct Q⁻. [(Ph₃P)₂PtQ]⁺BPh₄⁻ was independently prepared from cis-[PtCl₂(PPh₃)₂] and HQ/Me₃N, and is the first example of a platinum 8-hydroxyquinolinate complex containing phosphine ligands.     

Bidimensional self-assembling of [Hg(RPhNNNPhR′)2] (R = acetyl, R′ = F) through metal-η-arene π-interactions and non classical C-H?O bonding: Synthesis and X-ray characterization of a bis diaryl asymmetric-substituted triazenide complex polymer of Hg(II)

Deprotonated 3-(2-fluorophenyl)-1-(4-acetylphenyl)triazene reacts with Hg(CH₃COO)₂ in tetrahydrofuran to give light yellow crystals of [Hg^II(RPhNNNPhR′)₂]_n (R = acetyl, R′ = F). The new polymeric triazenide complex of Hg(II) belongs to the monoclinic space group C2/c. The lattice of [Hg^II(RPhNNNPhR′)₂]_n can be viewed as a bidimensional assembly of planar tectons [Hg^II(RPhNNNPhR′)₂], occurring through metallocene alike Hg(II)-η²,η²-arene π-interactions along the crystallographic axis b and non classical C-H?O bonding along the axis a.     

Preparation of trihydridostannyl complexes of rhenium stabilised by isocyanide ligands

Mixed-ligand complexes [ReBr(CO)₂(CNR)_nL_3−n] (1-4) [R = 4-CH₃OC₆H₄, 4-CH₃C₆H₄, C(CH₃)₃; L = P(OEt)₃, PPh(OEt)₂; n = 1, 2] were prepared by allowing carbonyl compounds [ReBr(CO)₄L] and [ReBr(CO)₃L₂] to react with an excess of isocyanide. Treatment of these bromocomplexes [ReBr(CO)₂(CNR)_nL_3−n] with SnCl₂ · 2H₂O yielded the trichlorostannyl derivatives [Re(SnCl₃)(CO)₂(CNR)_nL_3−n] (5-8). Trihydridestannyl complexes [Re(SnH₃)(CO)₂(CNR)_nL_3−n] (9-12) were prepared by allowing trichlorostannyl compounds 5-8 to react with NaBH₄ in ethanol. The trimethylstannyl derivative [Re(SnMe₃)(CO)₂(CNC₆H₄-4-CH₃){PPh(OEt)₂}₂] (13b) was also prepared by treating [Re(SnCl₃)(CO)₂(CNC₆H₄-4-CH₃){PPh(OEt)₂}₂] with an excess of MgBrMe in diethylether. Reaction of the tin trihydride complexes [Re(SnH₃)(CO)₂(CNR)_nL_3−n] (9-12) with CO₂ (1 atm) led to dinuclear OH-bridging bis(formate) derivatives [Re{Sn(OC(H)O)₂(μ-OH)}(CO)₂(CNR)_nL_3−n]₂ (14, 15). The complexes were characterised spectroscopically (IR, ¹H, ³¹P, ¹³C, ¹¹⁹Sn NMR) and by X-ray crystal structure determination of [Re(SnH₃)(CO)₂{CNC(CH₃)₃}{PPh(OEt)₂}₂] (10b).     

Synthesis of cyclopentadienyl ruthenium(II) complexes containing tethered functionalities

The reaction of [C₅H₄(CH₂)_nX]Tl (1: n = 2, X = NMe₂, OMe, CN; n = 3, X = NMe₂) with [(η⁶-C₆H₆)RuCl(μ-Cl)]₂, 2, afforded the sandwich compounds [{η⁵-C₅H₄(CH₂)_nX}Ru(η⁶-C₆H₆)]PF₆, 3, and [η⁵-C₅H₄(CH₂)_nX]₂Ru, 4. Photolytic cleavage of 3 in acetonitrile afforded the tethered products [{η⁵:κN-C₅H₄(CH₂)_nX}Ru(CH₃CN)₂]PF₆, 5.     

Properties of homo- and heteronuclear mixed biscarbene complexes with conjugated bithiophene units

The syntheses and structures of homo- and heteronuclear biscarbene complexes with bithiophene spacers were investigated. The complexes were synthesized by lithiation of bithiophene followed by metallation using combinations of the metal precursors MnMeCp(CO)₃, W(CO)₆, Mo(CO)₆ and Cr(CO)₆, after which the reaction was quenched with triethyloxonium tetrafluoroborate. This classical Fischer method yielded monocarbene complexes, [ML_nC(OEt)C₄H₂S-C₄H₃S], ([ML_n] = Cr(CO)₅1a, W(CO)₅2a or MnMeCp(CO)₂3a), homonuclear biscarbene complexes, [ML_nC(OEt)C₄H₂S-C₄H₂SC(OEt)ML_n], ([ML_n] = Cr(CO)₅1b, W(CO)₅2b or MnMeCp(CO)₂3b) and heteronuclear biscarbene complexes, [ML_nC(OEt)C₄H₂S-C₄H₂SC(OEt)M′L_n] (1d: [ML_n] = Cr(CO)₅ and [M′L_n] = W(CO)₅; 1e: [ML_n] = MnMeCp(CO)₂ and [M′L_n] = Cr(CO)₅; 1f: [ML_n] = Cr(CO)₅ and [M′] = Mo(CO)₅); 2d: [ML_n] = MnMeCp(CO)₂ and [M′L_n] = W(CO)₅; 3c: [ML_n] = MnMeCp(CO)₂ and [M′L_n] = Mo(CO)₅). Electron density calculations with the gaussian03 software package of 1e revealed a polar rod with the negative pole towards the chromium carbene side, whereas the biscarbenes 1d and 1b showed very little polarity. By-products resulting from activation of the carbene moieties in homonuclear biscarbene complexes included (i) ester-type complexes of the form [ML_nC(OEt)C₄H₂S-C₄H₂SC(O)OEt], ([ML_n] = Cr(CO)₅1c or W(CO)₅2c), formed in situ in the reaction of 1b and 2b, (ii) the organic bis-ester compound [EtOC(O)C₄H₂S-C₄H₂SC(O)OEt] 4, where both metal moieties had been substituted by oxygen and (iii) the carbon-carbon coupled dimeric bithienyl compound [C₄H₃S-C₄H₂SC(O)C(O)C₄H₂S-C₄H₃S] 5. By-products obtained from heteronuclear biscarbene reactions contain the former diketo compound (or a derivative) as spacer between two metal carbonyl fragments and have the general formula [ML_nC(OEt)C₄H₂S-C₄H₂SCR-CR′C₄H₂S-C₄H₂SC(OEt)ML_n] (5a: [M] = Cr(CO)₅, R = OH, R′ = OEt; 5b: [M] = W(CO)₅, R = R′ = O; 5c: [M] = Mo(CO)₅, R = R′ = O). Reaction of 1d, 1e and 1f with hex-3-yne resulted in the formation of benzannulated products 6a, 6b and 6c. All novel complexes were fully characterized using various spectroscopic techniques. The crystal structures of 1b, 2a and 5 are reported.     

Further studies on the dialkylation chemistry of [Pt2(μ-S)2(PPh3)4] with activated alkyl halides RC(O)CH2X (X = Cl, Br)

Further studies have been carried out into the reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards a range of activated alkylating agents of the type RC(O)CH₂X (R = organic moiety, e.g. phenyl, pyrenyl; X = Cl, Br). Alkylation of both sulfide centers is observed for PhC(O)CH₂Br, 3-(bromoacetyl)coumarin [CouC(O)CH₂Br], and 1-(bromoacetyl)pyrene [PyrC(O)CH₂Br], giving dications [Pt₂{μ-SCH₂C(O)R}₂(PPh₃)₄]²⁺, isolated as their PF₆⁻ salts. The X-ray structure of [Pt₂{μ-SCH₂C(O)Ph}₂(PPh₃)₄](PF₆)₂ shows the presence of short Pt?O contacts. In contrast, the corresponding chloro compounds [typified by PhC(O)CH₂Cl] and imino analogues [e.g. PhC(NOH)CH₂Br] do not dialkylate [Pt₂(μ-S)₂(PPh₃)₄]. The ability of PhC(O)CH₂Br to dialkylate [Pt₂(μ-S)₂(PPh₃)₄] allows the synthesis of new mixed-alkyl dithiolate derivatives of the type [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₄]²⁺ (R = Et or n-Bu), through alkylation of in situ-generated monoalkylated compounds [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (from [Pt₂(μ-S)₂(PPh₃)₄] and excess RBr). In these heterodialkylated systems ligand replacement of PPh₃ occurs by the bromide ions in the reaction mixture forming monocations [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]⁺. This ligand substitution can be easily suppressed by addition of PPh₃ to the reaction mixture. The complex [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ was crystallographically characterized. X-ray crystal structures of the bromide-containing complexes [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]⁺ (R = Et, Bu) are also reported. In both structures the coordinated bromide is trans to the SCH₂C(O)Ph ligand, which adopts an axial position, while the ethyl and butyl substituents adopt equatorial positions, in contrast to the structures of the dialkylated complexes [Pt₂{μ-SCH₂C(O)Ph}₂(PPh₃)₄]²⁺ and [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ (and many other known analogues) where both alkyl groups adopt axial positions.     

Reactivity of [MO] (M = Tc, Re) core towards 2-mercapto-1,3-azole ligands. Formation of a new organometallic complex of Re(IV) and X-ray crystal structures

Imidazole-2-thiol derivatives H₂L^1-3 (H₂L¹ = 1H-benzoimidazole-2-thiol, H₂L² = 5-methyl-1H-benzoimidazole-2-thiol, and H₂L³ = 1H-imidazole-2-thiol) act as neutral monodentate ligands in a number of technetium and rhenium complexes. Disubstituted M(V) (M = Tc, Re) complexes of the type [AsPh₄]{[MOCl₂(H₂Lⁿ)₂(H₂O)]Cl₂} are formed when [MOCl₄]⁻ react with H₂L^1-3 in 1:2 stoichiometric ratio. Single crystal X-ray structure determinations were carried out on [AsPh₄]{[TcOCl₂(H₂L¹)₂(H₂O)]Cl₂}. The coordination sphere is pseudo-octahedral in which the sulfur atoms of two ligands sit in the equatorial plane and a water molecule is in trans to the TcO multiple bond. All the complexes react with an excess of the corresponding ligand to form tetrasubstituted cationic species {[MO(H₂Lⁿ)₄]Cl₃}. These complexes can be also isolated by reaction of [MOCl₄]⁻ with an excess of ligand. No complex is obtained with benzothiazole-2-thiol (HL⁴) and benzoxazole-2-thiol (HL⁵). Ligand exchange reactions of [ReOCl₃(PPh₃)₂] with HL^4,5 have also been investigated. Treating the oxo-precursor with HL⁴ no product is isolated, while with HL⁵ the chelate oxo-compound [ReOCl₂(L⁵)(PPh₃)] is formed as two isomers. An interesting organometallic complex of Re(IV) [ReCl₃(L^5∗)(PPh₃)₂] is obtained when a slight excess of HL⁵ reacts with [ReOCl₃(PPh₃)₂] in refluxing benzene solution and in air. Geometry about the Re atom is approximately octahedral in which the equatorial plane contains three Cl atoms and the carbon atom of the benzoxazole ligand anion, the apical positions are occupied by two PPh₃. The reaction with O-ethyl S-hydrogen p-tolyl carbonothioimidate HL⁶ which contains the same heteroatoms of HL⁵ does not form an organometallic species, but forms the chelate oxo-Re(V) complex [ReOCl₂(L⁶)(PPh₃)]. The solid-state structure has been authenticated by X-ray crystallography.     

C-ansa-zirconocene complexes with O/S donor ligands: Novel homoleptic six coordinate 4-mercaptophenolate complex of Zr(IV)

New C-ansa-zirconocene complexes containing methoxythiophenolate and mercaptophenolate ligands have been synthesized and characterized. The reaction of (HSC₆H₄-n-OMe) (n = 2, 3 or 4) with [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}Me₂] (1) led to the formation of monosubstituted complexes [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}Me(κ,S-SC₆H₄-n-OMe)] (n = 2 (2); n = 3 (3)) and the disubstituted complex [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}(κ,S-SC₆H₄-4-OMe)₂] (4). The complexes [Zr{(R)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}(κ,O-OC₆H₄-4-SH)₂] (R = t-Bu (6); R = CH₂CHCH₂ (7)) and [Zr(η⁵-C₅H₄)₂(OC₆H₄-n-SH)₂] (n = 3 (9); n = 4 (10)) have been synthesized using the corresponding dimethyl zirconocene and mercaptophenol. However, the reaction of [Zr{(t-Bu)HC(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂] (11) with 4-mercaptophenol in the presence of NEt₃ led to the formation of the first example of a homoleptic six-coordinate mercaptophenolate complex of zirconium, namely [HNEt₃]₂[Zr(κ,O-OC₆H₄-4-SH)₆] (12). Complex 12 can be obtained in higher yield by the reaction of ZrCl₄ with six equivalents of 4-mercaptophenol and NEt_3. The reaction of 12 with [Zr(η⁵-C₅H₄)₂Cl₂] gave the unexpected disubstituted complex [Zr(η⁵-C₅H₄)₂(OC₆H₄-4-SH)₂] (10). The molecular structures of 4 and 12 have been determined by single-crystal X-ray diffraction studies.     

Synthesis and characterization of silver(I) derivatives containing acylpyrazolonate and phosphino ligands: X-ray crystal structures of monomeric [Ag(Q)(PPh3)2] and of dimeric [{Ag(Q)(PiBu3)}2] (Q = 1-phenyl-3-methyl-4-tert-butylacetylpyrazolon-5-ato)

New silver(I) acylpyrazolonate derivatives [Ag(Q)], [Ag(Q)(PR₃)]₂ and [Ag(Q)(PR₃)₂] (HQ = 1-R¹-3-methyl-4-R²(CO)pyrazol-5-one, HQ^Bn = R¹ = C₆H₅, R² = CH₂C₆H₅; HQ^CHPh2 = R¹ = C₆H₅, R² = CH(C₆H₅)₂; HQ^nPe = R¹ = C₆H₅, R² = CH₂C(CH₃)₃; HQ^tBu = R¹ = C₆H₅, R² = C(CH₃)₃; HQ^fMe = R¹ = C₆H₄-p-CF₃, R² = CF₃; HQ^fEt = R¹ = C₆H₅, R² = CF₂CF₃; R = Ph or iBu) have been synthesized and characterized in the solid state and solution. The crystal structure of 1-(4-trifluoromethylphenyl)-3-methyl-5-pyrazolone, the precursor of proligand HQ^fMe and of derivatives [Ag(Q^nPe)(PPh₃)₂] and [Ag(Q^nPe)(PiBu₃)]₂ have been investigated. [Ag(Q^nPe)(PPh₃)₂] is a mononuclear compound with a silver atom in a tetrahedrally distorted AgO₂P₂ environment, whereas [Ag(Q^nPe)(PiBu₃)]₂ is a dinuclear compound with two O₂N-exotridentate bridging acylpyrazolonate ligands connecting both silver atoms, their coordination environment being completed by a phosphine ligand.     

Palladium(II) and platinum(II) monoselenocarboxylates: Synthesis, spectroscopy, structure and their use as molecular precursors for metal selenides

Treatment of MCl₂(P^∩P) or MCl₂(PⁿPr₃)₂ with two equivalents of ArCOSeK readily yields cis-[M(SeCOAr)₂(P^∩P)] and trans-[M(SeCOAr)₂(PⁿPr₃)₂], respectively (M = Pd or Pt; Ar = Ph or 4-MeC₆H₄; P^∩P = dppm, dppe, dppp). The reaction of Pd(SeCOAr)₂(dppe) with PdCl₂(dppe) in the presence of NaBPh₄ in methanol gave a tri-nuclear ionic complex, [Pd₃(μ₃-Se)₂(dppe)₃][BPh₄]₂. These complexes were characterized by UV-Vis, IR and NMR spectroscopy. The complex [Pt(SeCOPh)₂(dppp)] has been structurally characterized by X-ray crystallography. The coordination environment around square planar platinum atom is defined by chelating dppp ligand and two unidentate selenocarboxylates bonded through selenium atoms. Pyrolysis of [Pd(SeCOAr)₂(PⁿPr₃)₂] either in tri-n-butylphosphate (TBP) (at 200 °C) or in the solid state (furnace heating at 350 °C) gave Pd₁₇Se₁₅.     

One-step synthesis and reduction of triphenylphosphine carbonyl palladium clusters of variable nuclearities

Heteroleptic triphenylphosphine carbonyl palladium clusters of different nuclearities were prepared under mild conditions by only varying the amount of ligand (PPh₃) used in the synthesis: three different clusters were successfully isolated after CO bubbling in a solution of [Pd₂(dba)₃] (dba = dibenzylideneacetone) with 3, 1 or 0.5 equiv of PPh₃, which led, respectively, to [Pd₄(CO)₅(PPh₃)₄] (1), [Pd₁₀(CO)₁₂(PPh₃)₆] (2) and [Pd_n(CO)_x(PPh₃)_y] (3) (n ≈ 24). The molecular structures of compounds 1 and 2 were determined by X-ray crystallography. The metal cores in these compounds were shown to consist in a butterfly for 1 and a bridged octahedron for 2. Compound 3 was shown to be at the boundary between molecular clusters and colloidal particles with tentative formulation arising from characterization data. These three clusters and the known [Pd₁₀(CO)₁₂(PBu₃)₆] and [Pd₁₂(CO)₁₅(PBu₃)₇] were submitted to NaBH₄ reduction. The Pd₄ cluster 1 did not react. The colloidal Pd_n species led to no isolable product. By contrast, the two Pd₁₀ and the Pd₁₂ clusters led to reduction products, isolated as salts. In the case of the reduced Pd₁₂ cluster, its structure was resolved by X-ray crystallography: the metal core consists of a face-capped octahedron. The reduced species reacted readily with Au(PPh₃)⁺, confirming their anionic nature.     

Reactivity of phenyldi(2-thienyl)phosphine towards group 7 metal carbonyls: Carbon-phosphorus bond activation

Addition of phenyldi(2-thienyl)phosphine (PPhTh₂) to [Re₂(CO)_10−n(NCMe)_n] (n = 1, 2) affords the substitution products [Re₂(CO)_10−n(PhPTh₂)_n] (1, 2) together with small amounts of fac-[ClRe(CO)₃(PPhTh₂)₂] (3) (n = 2). Reaction of [Re₂(CO)₁₀] with PPhTh₂ in refluxing xylene affords a mixture which includes 2, [Re₂(CO)₇(PPhTh₂)(μ-PPhTh)(μ-H)] (4), [Re₂(CO)₇(PPhTh₂)(μ-PPhTh)(μ-η¹,κ¹(S)-C₄H₃S)] (5) and mer-[HRe(CO)₃(PPhTh₂)₂] (6). Phosphido-bridged 4 and 5 are formed by the carbon-phosphorus bond cleavage of the coordinated PPhTh₂ ligand, the cleaved thienyl group being retained in the latter. Reaction of [Mn₂(CO)₁₀] with PPhTh₂ in refluxing toluene affords [Mn₂(CO)₉(PPhTh₂)] (7) and the carbon-phosphorus bond cleavage products [Mn₂(CO)₆(μ-PPhTh)(μ-η¹,η⁵-C₄H₃S)] (8) and [Mn₂(CO)₅(PPhTh₂)(μ-PPhTh)(μ-η¹,η⁵-C₄H₃S)] (9). Both 8 and 9 contain a bridging thienyl ligand which is bonded to one manganese atom in a η⁵-fashion.     

Anionic ruthenium(II) alkyls with ancillary diene and dienyl ligands: Synthesis and structures of [(η,η-C7H8)RuMe4] and [(η,η-C8H11)RuMe3]

Treatment of the ruthenium(II) diene complexes [(η²,η²-nbd)RuCl₂]_n or [(η²,η²-cod)RuCl₂]_n with 4 equiv. of methyllithium in the presence of N,N,N′,N′-tetramethylethylenediamine (tmed) yields the methyl complexes [Li(tmed)]₂[(η²,η²-nbd)RuMe₄] (1) and [Li(tmed)]₂[(η³,η²-C₈H₁₁)RuMe₃] (2), respectively, where nbd = norbornadiene and cod = 1,5-cyclooctadiene. In the latter compound, the cyclooctadiene ligand has been deprotonated to afford a η³,η²-1,2,3:5,6-cyclooctadienyl group. Both complexes were studied by ¹H and ¹³C{¹H} NMR spectroscopy, and the crystal structure of 2 was determined. One lithium atom in 2 is four-coordinate and bridges between one ruthenium-bound methyl group and one of the wingtip allylic carbon atoms in the η³,η²-C₈H₁₁ ligand. The other lithium atom is five-coordinate, and forms contacts with the other two Ru-Me groups and with the other wingtip carbon atom of the allyl unit.